Looking at the Steel Defender description, it appears that your steel defender may not be able to interact with or pick up an object. Is that how you all read it?  If I had a two-legged steel defender with hands, what could I do with those hands other than attack?

Out of combat, you can order it to do anything it can do normally. Every creature can take the Use an Object action. It’s only in combat that the feature text limits what action it can be commanded to take.

If it is the more-or-less free item interaction a creature can take as part of their movement or action, then I do not see anything in the rules that indicates that a Steel Defender cannot scoop up a dropped weapon, open a container, or open a door while moving provided its shape is capable of such a thing. However, the exclusion of the Use an Object action from the list of actions the Steel Defender can take does indicate that it cannot interact with an object in such a way that it requires a whole action. Another thing to keep in mind is that if a Steel Defender with say a rough canine shape is holding something in its "mouth" which it has always used for its force-empowered rend, then it is perfectly reasonable for the DM to rule that the Steel Defender cannot use that ability while keeping a hold of the item.

However, always remember that dropping something (be it an object or concentration) does not require any kind of action.